Highlighting growth regulation processes in fish populations by a simplex simulation approach: application to Merluccius hubbsi stocks in the Southwestern Atlantic

Abstract

Abstract A new simplex-based simulation approach (Spx) was developed to highlight multidirectional and multi-scale relationships between morphometric variables helping to functionally differentiate biological (fish) groups for better stocks definition and monitoring. Application concerned Merluccius hubbsi sampled in 1968–1972 and 2004 in six Southwestern Atlantic areas. Simulation results highlighted negative trends opposing front to back compartments indicating competition for body biomass distribution. However, top and bottom parts within these compartments were positively correlated indicating cooperative processes in favour of target local growth regulation. Positive and negative trends of growth regulation were also highlighted at lower body scale, notably between smaller components constituting body front compartment. On a geographical scale, average regulation levels of same morphometric variables showed monotonic or alternated variations between successive fish groups. This highlighted target and modulated growth regulations governing biomass distribution in different body parts by geographical-dependent ways. Under dynamical aspect (1968–1972 vs. 2004), growth regulation of mouth tended to increase with time leading to conclude on morphometric responses of M. hubbsi to overfishing pressure. Spx results were confirmed by several traditional approaches which showed less integrative aspect.